The prior art proposes numerous sheet holders that are useful for holding one sheet, or a relatively small stack of sheet-shape materials such as, for examples, sheets of paper, metal foils, plastic films, or the likes, in a freely suspended attitude along typically a vertical surface such as a wall surface, a door surface, or the likes.
Sheet holders of the prior art are generally represented by a substantially elongated assembly that is typically attached horizontally at a suitable height along a vertical wall surface or a similar vertical support structure. The assembly further generally defines at least one elongated slot along a longitudinal lower front edge thereof for inserting therein the upper edge of one, or a stack of more than one, sheet. The most common sheet holders of the prior art are for holding sheets of paper used in office environments. Sheet gripping means are provided within the cavity of the slot for holding therein an upper edge portion of the sheets.
In some instances, the sheet gripping means are represented by spring loaded gripping elements that need to be simultaneously operated with one hand through a button or small lever while the sheets of paper are inserted in, or retrieved from, the slot using the other hand.
In other instances, the paper gripping means is generally represented by a series of free rolling and gravity operated roller balls or relatively small cylindrical elements that are equidistantly distributed along a lower horizontal edge within the sheet holder. Once the sheets have been inserted in the slot, the roller balls or cylindrical elements freely roll down in the slot to contact with and sufficiently press the sheets against a rear member of the sheet holder. In these instances, only the sheets of paper need to be manipulated in order to insert or retrieve the latter from the sheet holder.
While these prior art sheet holders can generally fulfill the main objective of holding one or more sheets such as sheets of paper in a suspended attitude along a wall surface or the like, they also generally entail one or more of the following disadvantages in achieving this same objective.
For example, the sheet holders of the prior art integrating spring loaded paper gripping means generally require two hands to operate, which is inconvenient. Furthermore, over time, the spring loaded elements generally impinge marks or dents in the surface of the sheets such as sheets of paper, which is generally not desirable either.
In the case of sheet holders of the prior art integrating gravity operated paper gripping means, these devices are typically more prone to holding the sheet at a slightly different angle than their original angle at which they were inserted through the input slot.
For example, the sheet holders integrating a series of individual roller elements, such as spherical rollers or cylindrical rollers, cannot ensure that these rollers all apply an equal gripping pressure against the sheets of paper, which results in an imbalance of load. Consequently, sheets of paper sometime eventually end up being held at an angle relative to the horizontal, or fall off the sheet holder. This problem is more present in sheet holders integrating free rolling cylindrical elements since their gripping pressure applied on the sheets are more evenly distributed along the length of the elements which, in turn, significantly reduces the gripping action on the sheets of paper.
Furthermore, in order to remove the sheets from sheet holders of the prior art integrating gravity operated paper gripping means, typically, the sheets must be forcibly pulled down against the engaging force of the roller elements, which often results in damaging marks on the surface of one or more sheets pulled therefrom.
Another disadvantage of the sheet holders of the prior art resides in that their gripping means are configured such that they are limited to hold sheets of material having surface characteristics closely corresponding to conventional thin sheets of paper used in offices. Thus, these devices can hardly be used to hold sheets made of different materials having varied surface characteristics such as is often encountered in industrial applications. For example, these sheet holders of the prior art can hardly be used for holding sheets of material made of felt, wet fiber-mat, shaggy carpets, semi-rigid textiles, tarpaulin sheets, sheets of soft or hard rubber or foam, corrugated rubber sheets, or the likes.
Against this background, there exists a need for a new and improved sheet holder.
It is a general object of the present invention to provide such a sheet holder.